All of this is on wiki. If you told us what stickers are easier to obtain that'd be nice C:

In my opinion Wiki is too 'crowded' to look at, there's too much information. I only posted NPC name + the items you need in total for a reason.

So if you check the amount of items needed you could take a guess for yourself to see which stickers are easier to obtain. (If you want help with that I could always suggest a few quests though, it's no problem for me.)

Either way, my guide is for players that want as much (base) EXP as possible, so they will level up and have no problem passing on to the next key quest. It's not really meant for higher levels that only want to hand in the stickers to complete a key quest's sticker part. If that's their sole purpose of doing these quests they could make nublets happy by buying their extra stickers :3